Chemical Element: protactinium

(Modern Latin: some say it comes from Greek proto, "first"; plus actinium, "ray"; so, “first actinium”; radioactive metal)

Chemical-Element Information

Symbol: Pa
Atomic number: 91
Year discovered: 1913 and 1917.

Discovered by: Kasimir Fajans (1887-1975) and O. H. Göring, in 1913; and by Otto Hahn (1879-1968), German physical chemist, and co-worker, Lise Meitner (1878-1968), Austrian physicist; in 1917, in Germany; as well as Frederick Soddy (1877-1956), and John A. Cranston, in England.

  • This was previously known as “protoactinium”; so called because, by the loss of an alpha particle, it forms “actinium”.
  • Protactinium is found in pitchblende and ores from Zaire and it is one of the rarest and most expensive naturally occurring elements.
  • Protactinium was identified by Fajans and Göring in 1913 who named the new element brevium (“brief”).
  • The metal itself was not isolated until 1934 when Aristid Grosse developed two methods.
  • One involved reduction of the pentoxide with a stream of electrons in a vacuum and the second involved heating iodide under vacuum.

Name in other languages:

French: protactinium

German: Protactinium

Italian: protoattinio

Spanish: protactinio

Information about other elements may be seen at this Chemical Elements List.

A special unit about words that include chemo-, chem- may be seen here.